Soil Erosion by Water

Time - 450minutes

Student Outcomes
Students will observe the interaction of soil and water, and sod and water; the students will observe and describe the different splatter marks the contents of the two tins make on the white paper and discuss the interaction on the systems and how this is similar to our own environment.

Materials

• pie tins with sod only for each group
• pie tins with soil only for each group
• plastic cups of water
• newspapers
• two sheets of plain white paper for each group

Vocabulary

• evidence of interaction
• interaction
• system
• environment

Focus

Ask students what they think soil erosion is and if they can give reasons why we have erosion in our environment.*

Procedure

Divide into groups of 4 and have getters come and get materials. "Eyes up here for directions. Put newspaper down on your table and then one piece of white paper over the newspaper. Now put your tin with soil only in the middle of the paper. What do you think will happen if we pour ½ of our cup of water into the tin, from a height of about 2 ft.?" (modeling height) "These two tins are our systems. One system is made up of soil only. The other system is made up of soil and grass or sod. Do you think pouring the water on the two different systems will make the water react differently? Let one student from your group hold the cup 2 feet above the tin with just the soil in it and pour ½ cup of water in it. What does your white paper look like?” (response) "These splatters were made from the water interacting with the soil. Draw a picture of what the pattern on your white paper looks like."

"Now, put a fresh sheet of white paper down and place your tin with the sod in the middle of the paper. If we pour ½ cup of water over the tin with sod, what do you think the splatters will look like? Will they be different? Draw on your paper what you think the spatters will look like."

"Let's find out. Let another student of your group pour the rest of the water on, at least 2 ft. above the tin. Now look at this sheet of paper. What do these splatters look like? Are they different? How did the water interact differently in the two systems? Draw a picture of this pattern on your white paper. Why do you think the patterns were different on the 2 pieces of paper? How were they different?"

"How do you define environment?" (where you live and around your home) "How do you think these pie tin demonstrations are similar to our environment? Where in our environment would you find bare soil? Where have you seen soil that has no protective covering? These are all places where we might find bare soil in our environment. Where would we find an area in our environment that is similar to the sod in this pan?" (hold up the pan with the sod) "This could also represent wooded areas or any area that has something that protects the soil from run-off water. What do you think the cup of water represents in our environment?" (rain) "This type of interaction of water hitting the soil is called erosion. Erosion means that the water, or rain, washes the soil away. What difference did you see in the pattern of the tin with only soil and the pattern of the sod? Which one had erosion occurred? How do you know? Why do you think erosion didn't occur in the other tin? So we know that grass helps catch the rain and keeps the soil from washing away, or eroding, but the dirt doesn't catch the rain, and therefore it gets washed away. So it is very important to stop erosion by planting grass and trees in our environment to keep our soil from being washed away. Let's clean up our tables by having our getters roll up the newspaper and white paper and throw them away. Someone else bring the pie tins up to the front of the room and put them in the large box and the getters can put the plastic cup over by the sink."

Questions for closure of the lesson

These are a few questions to monitor their understanding of the lesson. This feedback would help you determine areas of comprehension and those which need to be covered more thoroughly. This questioning would be in lieu of a test because more is gained from experience and discussion.

1. "What is it called when two or more things come together and something happens?" (interaction) "Can you give me an example from today?" (water and soil)
2. "What did our pie tins represent?" (sod system and a soil system)
3. "What was the term we used to describe our surroundings?" (environment)
4. "When the water interacted with our tin of soil, what did we say occurred?" (erosion)
5. "Did erosion occur with the tin of sod?" (no)
6. "Which tin had the least erosion?" (sod tin) "Why?" (Because the grass helped soak up the water; roots may have helped old soil; grass may have softened the force of the rain.)
7. "What other ways can we help prevent erosion?"

Notes:

*If you are aware of evidence of soil erosion around your school yard, take the children to the site as your focus.

Recycle the soil.